Code 25: Mat Sensor Temp High: Notes
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The ECM applies and monitors a voltage signal (4-6 volts) to MAT sensor. When manifold air is cold, the sensor resistance is high and the ECM will see a high signal voltage. As air warms, resistance decreases and voltage sensed by the ECM drops. Sensor resistance can be measured at sensor terminals with harness disconnected.
NOTE:
Test numbers refer to test numbers on diagnostic chart.
- This checks if the code is a hard failure or an intermittent condition. Code 25 will set if a MAT temperature greater than 275°F (135°C) is sensed for more than 2 seconds.